I’d say late-game tedium is Ascendancy’s biggest issue. I’ve since learned that if I aim to finish a game, it’s better to select the smaller (vacuous/sparse) map sizes.
Also, while there is a (not great) auto-colony manager, the purely mouse-based interface annoyed me enough to make Autohotkey helper scripts to add some useful hotkeys, mostly for building. If someone’s interested, I can share them (some assembly required though).